Happy 80th birthday, Nigel Lawson. Unhappily for the rest of us, your principles of taxation – make ’em simple, low and compulsory – were trashed by Complexity Brown, the man who doubled the length of Tolley’s tax bible and allowed the banks to fiddle their way out of paying.

Chancellor Lawson also had an alternative to the Lib-Dems’ Mansion Tax. Noting the hideous complexity of changing residential property taxation, he considered a reform to set the level by reference to the price at which a dwelling changed hands. Thus, the National Treasure in Kensington’s Scarsdale Villas who has lived there for decades would pay a rate based on his original purchase price, while the hedge fund manager next door who had just paid £5 million would pay the same percentage of his purchase price.

In practice, there are almost as many problems with this scheme as with the Lib-Dems’ pet project – how to treat home improvements, for example, or how to rate houses which are not sold – and George Osborne’s second Budget may not even add a higher Council Tax band for those of us in good houses in a nice part of town. It wouldn’t raise much, but equality of misery is politically important in a time of austerity.

A far more potent source of revenue is the tax relief on pension contributions. There is no logic in allowing higher rate taxpayers twice the relief offered to basic rate payers. Indeed, the premise that higher earners need higher pensions and thus deserve bigger incentives is positively perverse, since common sense would suggest the opposite. The counter-argument, that pensions are taxed on receipt, looks thin in the context of the 25% tax-free lump sum.

At present, thanks to one of Blundering Brown’s more bizarre rule changes, the vast majority of the tax relief on pension contributions goes to the few at the top of the income ladder. Leaks to the FT suggest that the current £50,000 cap on annual contributions could be cut to £30,000, but like the wretched upper income tax band, this raises little revenue. Cutting both higher rate relief on contributions and the top rate on incomes would defuse the sterile arguments about whether there is anything more than political point-scoring in 50% income tax.

No Budget is complete without a fresh addition to the tax-planner’s handbook, so here comes the Seed Enterprise Investment Scheme. This is so generous that the European Commission is yet to approve it under the rules on state aid. Investors in start-ups get 50% income tax relief, and corresponding capital gains realised in 2012/13 will be tax free. The credits add up to 78% of the cost. No wonder it’s rationed to £150,000 per investor.

The SEIS joins its elder brothers, the VCT and the EIS, which are proving the old rule that today’s tax incentive is tomorrow’s tax avoidance vehicle. The latest wheeze is the enhanced buyback. Buried in the impenetrable verbiage that VCT investors get with these offers is a simple idea: swap existing shares in return for equivalent new ones (less costs) and, hey presto, you can claim 30% income tax relief without putting up any new money.

The taxman has tolerated these devices, but they hardly comply with the spirit of the rules, and with £7 billion now invested in both schemes, it’s time they were stopped. The VCT managers could turn their attention to generating a proper secondary market in their shares instead.

The SEIS may encourage start-ups, and create some jobs. Far better would be to scrap the cat’s-cradle of employment laws for the smallest companies, allowing freedom of contract between employer and worker for businesses employing fewer than, say, 25 people. Now there’s a reform that Lord Lawson would welcome. The EC would claim it breached its employment protection rules. Lawson would probably approve of that, too.